The field of the disclosure relates generally to distribution of flux from a power beam, and more specifically, to methods and systems for improving flux distribution for an optical heat exchanger.
Most modern spacecraft or aircraft rely on chemical propulsion, for example, the burning of a fuel and oxidizer to produce both energy and reaction mass. Various engine designs are used to convert this energy and reaction mass into thrust. Performance of these propulsion schemes is limited by the energy of chemical reactions and by the molecular mass of the reaction products, e.g., H2O and CO2.
Alternative approaches have been examined and, increasingly, implemented. These frequently use a non-chemical energy source, such as an external beam of electromagnetic energy, to heat the propellant. By eliminating the need for combustion, the propellant can be chosen to have low molecular mass, and therefore a higher exhaust speed for a given temperature. Since engine materials are limited by the peak temperature at which they can operate, the beamed energy approach allows higher exhaust speed (and therefore higher specific impulse) than chemical propulsion.
In the operation of a beam-powered rocket vehicle and a beam source, a key component of the system is the beam receiver. This component collects the beam and transfers its energy into the propellant as heat. The specific device for the transfer of energy into the propellant as heat within the rocket vehicle is a heat exchanger laser thruster. In this regard, a beam of electromagnetic energy (typically a laser beam) impinges on a set of tubes disposed within the heat exchanger. The tubes are typically arranged on a flat plate and are evenly spaced. Outer surfaces or walls of the each tube absorbs the electromagnetic energy as heat and transfers the heat to the propellant. Each tube then carries a fraction of the propellant that flows from a tank into the nozzle of an engine as heated propellant.